Can-do coolant strategies

With the cost of high-performance coolants on the rise, coolant management is more important than ever. It starts by getting the basics right.

If you are paying $8 to $12 per gal. for coolant and are satisfied with the cleanliness and sump life, the coolant produces no odors and operators love working with it, don’t bother to read this article. If you feel you are paying too much for coolant and not getting the performance and payback you expect, read on.

This article’s purpose is to arm you with some basic information to gain control of coolants, improve the shop environment and lower costs. This information will help you deal with and evaluate suppliers of coolant products, equipment and services.

Courtesy of Rego-Fix

Coolants have ingredients for machining, rust prevention, bacteria control, pH stability and other functions. When a coolant is in use, these ingredients are consumed at different rates, depending on the metals being machined and type of machining.

Coolant development has been spurred by several factors, including the rising cost of additives, chlorinated paraffin and oil, and the need to keep pace with changes in the machine tool industry. As new coolant technology is developed, coolant prices typically increase, reflecting the performance improvements and the cost of raw materials.

Coolants now sell for $15 to $28 per gal. or more, so a new look at coolant management and recycling to maximize return on investment (ROI) is warranted.

The term “coolant management” is commonly used to describe the actions and equipment required to maintain coolants at their maximum performance level. The first step in implementing a coolant management program typically involves calling manufacturers of coolant recycling, filtration and oil skimming equipment. These companies will survey your plant and estimate the equipment needed. Savings will be itemized in many categories, including gal. of coolant purchased and reduced waste disposal and machine downtime. They usually provide a projected ROI as well.

At this point, many manufacturers are in a rush to get started. Not so fast! In reality, many of these equipment installations will not generate the promised ROI. Visits to many shops show large numbers of centrifuges, coalescers and filters sitting unused. Why? Largely because the steps to control coolant on a day-to-day basis were not incorporated with the purchase of equipment.

Rule No. 1 is you must implement operational coolant control before purchasing coolant recycling and filtration equipment. Most of the factors that determine the success or failure of coolant management programs can be done with minor, noncapital investment. Start by keeping records, selecting an effective base coolant for the program, controlling the concentration and cleaning coolant sumps on a regular basis.

Record Keeping

Each operator should have a logbook to track the coolant concentration and sump life for his machine. Readings for pH and bacteria are optional and can be delayed until you get further into your coolant management program. Note any unusual occurrences that affect the coolant. A well-kept logbook will provide your coolant supplier with valuable information should problems develop.

Machine ID: unit 21Sump capacity: 50 gal.Date Charged: 07-10-08Coolant: Kool Rite 2290Recommended concentration: 7%Recommended refractive index: 1.3DateConcentrationpHBacteriaComments. Note additions, problems, sump cleanouts11-11-085.5/7%9.10Water added from dispenser at 2.5 percent11-12-084.5/5.85%9.10Hydraulic line break, excess tramp oil vacuumed out

Use the coolant usage information as a baseline to judge the impact of future coolant management changes. Consider tracking your current coolant situation for 3 to 6 months before examining equipment. It is critical to know the sump capacity for each machine and the shop’s total. If you can’t find the sump size as specified by the manufacturer, you can determine it easily. Measure the sump’s width and length and coolant depth at the normal operating level in feet. To determine sump capacity in gal., multiply width × length × liquid height × 7.5.

Courtesy of Haas Automation

Coolant development has been spurred by several factors, including the rising cost of additives, chlorinated paraffin and oil.

Coolant Selection

Lower-priced coolants typically do not contain biocides at high enough levels to control bacteria. They contain six to 10 ingredients, use low-cost emulsifiers and little pH buffering. More advanced, pricier coolants provide increased performance by combining 16 to 20 ingredients at optimal levels.

Why spend the money for advanced technology? Coolants are never the same once put to use. You can add coolant to the sump but the resulting coolant will always be a different mix of chemistries than the virgin coolant. The reason is selective depletion. Coolants have ingredients for machining, rust prevention, bacteria control, pH stability and other functions. When a coolant is in use, these ingredients are consumed at different rates, depending on the metals being machined and type of machining.

The most obvious example of this is when odor from bacteria is present even though the coolant is at the proper concentration. This is because the biocide has been selectively depleted faster than the other components. With a central control system, selective depletion many times requires adding ingredients, such as pH buffers and biocides, in addition to replenishing the coolant.

Traditional coolants come in three categories:

• Soluble oils, which are actually emulsified oils that combine petroleum or vegetable oil and water.

• Semisynthetics are made with lower amounts of oil than soluble oils and utilize synthetic additives to some degree.

• Synthetics are made without any oil.